Chain assemblies with minimal pin projection

ABSTRACT

A chain assembly has pins extending through the guide links with minimal projection beyond the outside edge of the guide links. The minimal pin projection provides a chain assembly of narrow construction. Modular chain systems are also provided that permit manufacturing savings in the construction of chain systems of standard widths.

This application is a continuation in part of U.S. application Ser. No.08/131,473, filed Oct. 4, 1993, entitled "Phased Chain Assemblies," nowU.S. Pat. No. 5,427,580, the subject matter of which is incorporatedherein by reference, which is a continuation in part of U.S. applicationSer. No. 07/885,194, filed May 19, 1992, now abandoned, the subjectmatter of which is also incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to power transmission chains.The invention has particular application to power transmission chains ofthe inverted tooth or silent chain variety, which are used in enginetiming applications as well as in the transfer of power from a torqueconverter to a transmission or in a transfer case of a four-wheel drivevehicle. The invention also has applications with roller chains andchain-belts for continuously variable transmissions (CVT).

Conventional silent chains utilize links with inverted teeth for thetransmission of power. Sets or rows of inverted tooth links areinterleaved and connected by pins to form the chain assembly. Typically,guide links are press fit on the pins and are included along theoutsides of both sides of the link rows to maintain the chain on thesprockets. The pins typically extend out beyond the edges of the guidelinks in the transverse direction of the chain, i.e., the directiontransverse to the longitudinal movement of the chain around thesprockets.

As explained below, in one embodiment of the present invention, the pinsare flush with the outside edges or sides of the outside links or guidelinks, or are constructed for minimal projection from the sides of theoutside links. Minimization of the projection of the pins allows anarrower chain construction and permits embodiments where the guidelinks of the two chains in side-by-side relation may also be in touchingrelation.

The present invention has particular application to chain assemblies inwhich the chains and sprockets are offset, or phased, to modify theimpact noise spectrum and chordal action noise spectrum. In a phasedchain system, a single chain assembly is divided into, or replaced by,two side-by-side chains that are phased or offset by one-half pitch. Inone embodiment of the present invention, the minimal pin projection isutilized on the sides of the two chains that are in the side-by-siderelationship. The guide links with the minimal pin projection are placedin a groove in the center between the phased sprockets. With the guidelinks in the center groove, the guide links on the opposite or outersides of the chains may be eliminated. Elimination of the guide links onone side of the chain, and running the guides links from the two chainsin the center groove in a side-by-side and touching relationship, allowsthe achievement of a narrower phased chain system than in certain phasedchain systems of the prior art.

As previously mentioned, silent chains are typically formed ofinterleaved sets of inverted tooth links. A set or rank of links isassembled from several links positioned alongside of or adjacent to eachother. The links are connected by pivot members or pins, which aretypically round pins or rocker joint pins received in a pair ofapertures. An example of silent chain is found in U.S. Pat. No.4,342,560, which is incorporated herein by reference.

Conventional silent chains typically include both guide links andinverted tooth links. The guide links are positioned on the outsideedges of alternate sets of links. The guide links typically act only toposition the chain laterally on the sprocket. Guide links do not meshwith the sprocket.

The inverted tooth links, or sprocket engaging links, provide thetransfer of power between the chain and sprocket. Each inverted toothlink includes a pair of apertures and a single depending tooth or a pairof depending toes or teeth. Each toe is defined by an inside flank andan outside flank. The inside flanks are joined at a crotch. The invertedtooth links are designed so that the links contact the sprocket teeth totransfer power between the chain assembly and the sprocket. The invertedtooth links, or driving links, contact the sprocket teeth along theirinside link flanks or their outside link flanks or combinations of bothflanks. The contacts between the links and the sprocket teeth can be ofthe type which provide a power transfer, or can be of the nature of anincidental contact, or can include root contact or side contact.

A conventional silent chain drive is comprised of an endless silentchain wrapped about at least two sprockets supported by shafts, Rotationof a driving sprocket causes power transmission through the chain andconsequent movement of a driven sprocket. In an engine timing driveapplication, the driving sprocket is mounted on the engine crankshaftand the driven sprocket mounted on the camshaft. A chain for an enginetiming drive application is shown in U.S. Pat. No. 4,758,210, which isincorporated herein by reference. Various types of engine timing systemsand configurations are also shown in U.S. application Ser. No.08/131,473, filed Oct. 4, 1993, now U.S. Pat. No. 5,427,580, which isincorporated herein by reference.

A second type of chain is known as "roller chain". A typical rollerchain consists of alternate inner links and outer links. The innerlinks, which are also known as "bushing" links, Consist of spacedsidebars with bushings tightly received in openings, or apertures, ateach end of the sidebars. The outer links, which are also known as "pin"links, consist of spaced sidebars with pins tightly received inopenings, or apertures, at each end of the sidebars. The bushings freelyrotate about the pins to pivotally connect the outer links to the innerlinks in alternate arrangement. Rollers are provided on the bushings,and when the roller chain is wrapped about a sprocket, the teeth of thesprocket are received between the laterally spaced sidebars and thelongitudinally spaced rollers. An example of roller chain is found inU.S. Pat. No. 4,186,617, which is incorporated herein by reference.

Roller chain drives can include both "true roller" and rollerlessdesign. The true roller design includes the described rollers mountedabout the bushings. Rollerless chain contains bushings that directlycontact the sprocket. Both types of roller chain are typically specifiedin industry as British Standard chain and American National StandardsInstitute (ANSI) chain.

Noise is associated with chain drives. Noise is generated by a varietyof sources, but in silent and roller chain drives it can be caused, inpart, by the impact sound generated by the collision of the chain andthe sprocket at the onset of meshing. The loudness of the impact soundis affected by, among other things, the impact velocity between thechain and the sprocket and the mass of chain links contacting thesprocket at a particular moment or time increment.

Many efforts have been made to decrease the overall noise level andpitch frequency noise distribution in chain drives of the silent chainvariety to minimize the objectionable effects of the pure sonic tones.Several of those efforts are discussed in the above-mentioned U.S.application Ser. No. 08/131,473, filed Oct. 4, 1993. The presentinvention finds application along with some of the noise reductionconcepts discussed in the above-mentioned application, includingrandomization and phasing of the chain assemblies. However, the presentinvention has broader applications to chain systems that include, forexample, non-phased sprockets or non-randomization of link profiles.

Phasing the chain and sprocket relationship can reduce the number ofchain link teeth (or mass) impacting the sprocket during a given timeincrement. Similarly, phasing the chain and sprocket relationship canalter or phase the chordal action or articulation of the chain andsprocket. The chain randomization and sprocket phasing modifications canalter the impact and chordal action generated sound patterns.

However, in the narrow chain assembly package requirements that areparticularly found in modern engine timing systems, the use of a phasedchain system can be difficult in that the single chain is often replacedby two chains that are placed in side-by-side and phased relation. Theneed to place two phased chains in side-by-side relationship in the samewidth previously occupied by a single chain requires elimination ofinside links or use of thinner inside links. (The term "inside link" or"inner link" is used to describe an articulating link, or link thatarticulates with respect to the pins, with teeth constructed to,drivethe sprocket, in contrast to conventional "guide links" that are pressfit and act to maintain the chain on the sprocket.) Such a modificationis disadvantageous in that it requires fewer inner links across thewidth of the chain, or thinner inner links across the chain, whichgenerally result in a weaker chain assembly than the assembly with agreater number of inner links across the width of the chain.

Modern engine timing systems often have as few as four links in thenon-guide row and four or five links in the guide row. (The term "guiderow" refers to the rows or sets of links along the length of the chainthat include guide links on the outsides, while the term "non-guide row"refers to the rows along the length of the chain that are interleavedwith the guide rows and do not include guide links on the outside.) Inorder to package such a narrow timing system in a phased system inapproximately the same width, without decreasing the link thickness, thechain system often requires the use of chains laced with as few as twolinks in the guide row and two links in the non-guide row, i.e., what isreferred to as a "2×2 lacing."

Silent chains typically utilize two conventional guide links, i.e.,guide links without inverted teeth that are designed to contact thesprocket and provide a driving force, in each guide row. In a 2×2lacing, such a construction results in every guide row, i.e., everyother row of the chain, not having a driving contact with the sprocket.Such a construction that fails to provide a driving or powertransmission contact with the sprocket in every row can result in anoisier chain than a chain in which every row has a driving contact withthe sprocket.

Moreover, phased chain systems as well as side-by-side non-phased chainsystems, are conventionally constructed with the two chains in aspaced-apart relationship. The spacing is provided between the twochains to assure that the chains do not contact one another duringoperation. In high speed automotive applications, significant movementoccurs in the portions of each chain that span the longitudinal spacebetween the driving and driven sprockets of each assembly. Theseparation between the two chains in the transverse direction isprovided to prevent any contact between the two chains during suchmovement. Clearances between the chain and other structures aretypically recommended in order to avoid contact from longitudinal ortransverse movement of the chain during operation. The separationdistance between the chains also contributes to the size or overallwidth of the chain package.

The present invention is directed to overcoming such disadvantages. Thepresent invention provides other advantages in decreasing the width ofthe package size of the phased chains or allowing more inner links in achain of the same width as without the present invention.

SUMMARY OF THE INVENTION

The present invention relates to a chain assembly in which the pins areplaced in the chain assembly with minimal projection beyond the outsidelinks of the chain. That is, the pins are preferably flush or do notproject beyond the edge of the outside links on at least one side in thetransverse direction of the chain. To the extent the pins extend beyondthe outside links, the extension is preferably limited to less than 50%of the thickness of the outside or outermost link, or more preferably,less than 10% of the thickness of the outside or outermost link.

In one embodiment of the present invention, a phased chain systemincludes two chains in side-by-side but offset or phased relation. Theprojection of the pins is limited on the sides of the two chains thatare in side-by-side relationship. The minimal projection of the pins mayallow the guide links of the chains to be in a touching relationship.

In one embodiment, the present invention provides a slot in the centerof, or between the two, phased sprockets. The guide links travel in thisslot in the center of the sprockets. As a result of the pins being flushagainst the links, or projecting only a minimal distance beyond theoutside edges of the links, the two side-by-side chain assemblies may beplaced close together and the guide links on the two chains are incontact with each other. By close placement of the two chains, theoverall system achieves a narrower width. Moreover, the guide links onthe opposite sides of each chain may be eliminated as the slot in thecenter of the sprockets provides a guiding function with the singleguide links.

The pins are placed flush with the outside link by driving the pins in adirection toward the center of the chain. Alternatively, the aperturemay be slightly relieved on the outside of the chain so that the pin mayseat in the aperture. The pin may be placed asymmetrically with respectto the transverse direction of the chain so that the pin extends agreater amount from one side of the chain than from the other side ofthe chain.

The pin need not be flush with the outside of the link, but shouldpreferably not extend very far outward in the transverse direction ofthe chain. In one embodiment the projection of the pin is limited toless than 50% of the thickness of the innermost link. (The term"innermost link" is used to define the link on the side of the chainthat, for example, is in side-by-side relation with an adjacent chain.In non-phased system, or in systems without side-by-side chains, eitherside of the chain may be defined as the "inner" side that includes an"innermost link.") In a more preferred embodiment, the projection of thepin is limited to less than 10% of the thickness of the innermost link.

In certain embodiments of the present invention, the guide link is inthe form of an inverted inside link. That is, the guide link resemblesan upside down inside link with a crotch between two upward extendingportions. Such guide links, with additional features, are shown, forexample, in U.S. application Ser. No. 08/196,310, filed Feb. 19, 1994,entitled "Chain Guide Link," to David White, now U.S. Pat. No.5,445,570, the disclosure of which is incorporated herein by reference.The guide link is thinner than the inside links, or driving links, andis located on the inside or innermost position of the chain. The outsideor outermost link of the chain is also thinner than the inside ordriving links. In contrast to the inside links, which are fit forarticulation with respect to the pins, the outside or outermost link ispress fit on the pins. The outermost link may include inverted teeth ormay resemble the innermost guide link. The inside links are preferablyconventional inside links with pairs of inverted teeth for drivinglycontacting the sprocket teeth. (The terms "outermost link" and"innermost link" are used to define a link in a particular row of links,and may define similar links in other rows of links.)

The present invention provides several advantages in decreasing thewidth of the chain assembly. In the small package sizes necessary formodern automotive engine timing chains, the elimination of the spacingbetween the two chains in the phased chain system provides such apackage size advantage. Moreover, the use of the center groove forplacement of the guide links allows elimination of guide links on theopposite side of the chain, which also contributes to a smaller packagesize for the chain. In addition to allowing a chain of lesser width, thepresent invention allows a pair of chains of greater numbers of drivingor inverted tooth inside links to fit in the same width of a pair ofchains without the guide links of the present invention.

The present invention also provides a novel form of guiding the twochains in a side-by-side relationship. In conventional chain systems,the two side-by-side chains are placed in a spaced apart relationship,with specified clearances, in order to avoid any contact between the twochains from longitudinal or transverse movements of the chain. In thepresent invention, the two chains are placed in a contacting or touchingrelationship so that each chain will guide the other chain. Such anapproach is contrary to the conventional teachings of avoiding contact.

The present invention has particular application with phased chainassemblies or systems. That is, high speed automotive transmission,transfer case or engine timing systems in which the sprockets are splitinto two portions or separate assemblies and the sprocket portions areoffset or phased with respect to one another, with single or multiplechains.

Each of these embodiments, as well as certain other embodiments, mayinclude a plurality of chain assemblies, including assemblies of two,three, or four chain strands. Additionally, the sprockets may be phased1/4, 1/3 or 1/2 tooth, as well as various other amounts of pitch.Likewise, the chain assemblies may be phased by 1/4, 1/3 or 1/2 pitch,or other amounts of pitch.

In each chain assembly, the links are interleaved to form sets of links.Each link includes a pair of apertures, with an aperture from one set oflinks being aligned for interlacing with an aperture from an adjacentset of links. Pivot members, in the form of round pins or rocker joints,are utilized to connect the adjacent sets of links through theapertures, and to allow pivoting of the sets of links with adjacentsets. In the case of silent chains, the driving links have invertedteeth for providing a power transmission with the sprocket. In the caseof roller chains, the links are interconnected and the sprocket iscontacted by either rollers or bushings.

The present invention also provides advantages in the modularconstruction of chain. In conventional chain assemblies for automotiveapplications, chains can be provided in widths of, for example, 0.750inch, 0.875 inch and 1.00 inch. In providing chains for these widths, anadditional link is added to each row. Thus, the 0.875 inch wide chainhas one additional link in each row than the 0.750 inch wide chain andthe 1.00 inch wide chain has one additional link in each row than the0,875 inch chain. In other words, each guide row of 0.875 inch chainincludes one more link than each corresponding guide row of 0.750 inchchain and each non-guide row of 0.875 inch chain includes one more linkthan each corresponding non-guide row of 0.750 inch chain.

In the present invention, modular chains are provided in two standardwidths. The width of the three conventional standard chains can be metwith various combinations of the two modular chains of one width; twochains of the second width; or, a chain of one width in combination witha chain of the second width. In providing phased systems for thesechains, the use of modular chains in various combinations avoids theneed for manufacture of an additional chain. Modular chains providemanufacturing savings and advantages in the preparation of phased chainassemblies for customers.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention, one should refer tothe embodiments illustrated in greater detail in the accompanyingdrawings and described below by way of examples of the invention. In thedrawings, which are not to scale:

FIG. 1 is a schematic illustration showing a portion of two phasedchains of the prior art in side-by-side relation;

FIG. 2 is a schematic illustration showing a portion of two phasedchains in one embodiment of the present invention in side-by-siderelation and illustrating the location of the pins within the links andthe pins contacting the guide links of the adjacent chain;

FIG. 2A is a schematic illustration showing a portion of two phasedchains in one embodiment of the present invention in side-by-siderelation and illustrating the location of the pins within the links at adistance approximately 10% of the thickness of the guide links.

FIG. 2A is a schematic illustration showing a portion of two phasedchains in one embodiment of the present invention in side-by-siderelation and illustrating the location of the pins within the links at adistance approximately 10% of the thickness of the guide links.

FIG. 3 is a top view illustration of a portion of a pair of modularchains of a first width having the minimal pin projection feature of thepresent invention;

FIG. 4 is a top view illustration of a portion of a pair of modularchains of a first and a second width having the minimal pin projectionfeature of the present invention;

FIG. 5 is a top view illustration of a portion of a pair of modularchains of a second width having the minimal pin projection feature ofthe present invention;

FIG. 6 is an illustration of a top view of a portion of a pair of phasedchains having the minimal pin projection feature of the presentinvention;

FIG. 7 is an illustration of a top view of a portion of a pair of phasedchains of the prior art;

FIG. 8 is a side view illustrating the three types of links of oneembodiment of the present invention, including the innermost guide link,the conventional inside link and the outer link;

FIG. 9 is a side view illustrating the interleaving of the links of FIG.8;

FIG. 10A is an illustration of the present invention with a timing chainsystem having a single camshaft and crankshaft;

FIG. 10B is a schematic side view of FIG. 10A illustrating the chains inphantom.

FIG. 11 is an illustration of the present invention with a timing chainsystem having a pair of overhead camshafts;

FIG. 12 is a schematic illustration of a method of manufacture of thepresent invention in which the pin is driven from the position in FIG.12A to the position in FIG. 12B where it is substantially flush with theoutside edge of the link;

FIG. 13 is a schematic illustration of a method of manufacture of thepresent invention in which the pin is set in a recess in the aperture ofthe link;

FIG. 14A is a schematic illustration of a welded pin in the prior artand FIG. 14B is a schematic illustration of a method of manufacture ofthe present invention in which the pin is welded in a recessed positionin the aperture.

FIG. 15 is an illustration of a top view of a portion of a pair ofphased chains having the pins extending beyond the guide links andcontacting the guide links of the adjacent chain.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As illustrated in the drawings, the present invention is directed toproviding a chain with pins set for minimal projection in the transversedirection of the chain. FIG. 1 illustrates a pair of phased chains 10,12 of the prior art in a side-by-side relationship. The two chainsinclude guide links 14, 16 along their outsides and inside orarticulating links 18 that have pairs of depending toes for drivingcontact with the sprockets. The two sprockets 20, 22 are phased oroffset by approximately one-half pitch.

As typical of the prior art, the pins 24 project outward from the sidesof the chain assembly at both sides of the chain. The pins are generallysymmetric (within manufacturing tolerances) with respect to thetransverse direction of the chain. The two chains 10, 12 shown in FIG. 1are in a separate and spaced apart relationship. The spacing is providedto prevent contact of the guide links of one chain with the guide linksof the adjacent chain. However, some chains of the prior art allowcontact between the projecting pins of the two chains. Examples of sucha prior art phased chain assembly are shown in Japanese unexaminedutility model application publication no. 5-17251 (application no.3-90363) and Japanese unexamined utility model application publicationno. 3-28348 (application no. 1-51389). These applications depictincidental contact between pins of adjacent chains.

FIG. 2 illustrates a pair of phased chains 24, 26 that utilize theminimal pin projection feature of the present invention. As seen in FIG.2A, the two chains include guide links 28, 30 that are located along theinside of the chains, that is, the parts of the two chains that are inthe side-by-side relationship, shown generally at 32. In thisembodiment, the pins do not project beyond the edges of the innermostguide links 28, 30. Accordingly, the two guide links are in a touchingrelationship as they travel about the sprocket. The guide links are alsoheld within the groove 34 between the two sprocket portions 36, 38. Theplacement of the lower portion 40 of the guide links in the groove 34maintains the chains on the sprockets. In this manner, the chains areable to guide each other by the contact between the guide links of theadjacent chains. In the embodiment of FIG. 2B, the guide links 28, 30are thinner than the inside or driving contact links 42, 44.

The "edge" of the guide link is the flat surface on the side of the linkin the transverse direction of the chain. The distance between the twoedges is the thickness of the link. The thickness is shown, for example,in the sectional view of FIG. 2. The pins 46 are allowed to projectbeyond the outside edges of the outermost links 48, 50. However, in theembodiment of FIG. 2A, the outermost links 48, 50 are thinner than theinside or driving contact links 42, 44. The pins are press fit into theoutside links in conventional fashion. The outside links have invertedteeth for power transmission contact with the sprockets.

The guide links 28, inside links 44 and outside links 48 of one chainassembly 24, are shown in more detail in FIGS. 8 and 9. The innermostlink 28 is a guide link that has a lower extending portion 40 thatmaintains the chain on the sprocket. The inside link 44 is aconventional articulating link with two depending teeth 52, 54 fordriving contact with the sprocket. The outside link 48, or outermostlink, is an inverted tooth link. The pin is preferably press fit on theoutermost link. Other combinations of links are also possible. Forexample, the guide link 40 may be an inverted tooth link. Similarly, theoutside link 48 may also be an inverted tooth link. Alternatively, theoutside link may be a traditional guide link. While only one inside link44 is shown in FIGS. 8 and 9, additional inside links may be interleavedto obtain a 2×2 or other lacing configuration. Lacings with additionalinside links are shown, for example, in FIGS. 3-6.

The fit of the pins 46 into the inside guide links 28 to achieve minimalpin projection is accomplished in any of a number of possible manners.Three methods of manufacture are illustrated in FIGS. 12, 13 and 14. Ofcourse, other methods of manufacture are possible and the invention isnot limited to the methods illustrated and described here.

In the method illustrated in FIG. 12, the pin is driven through the linkuntil it extends outside the guide link 28, as shown in FIG. 12A. Afterthe head of the pin is riveted, then the pin is driven back into theguide link to the point where the desired projection is achieved, asshown in FIG. 12B. The pin head may extend beyond the end of the link,but preferably is substantially flush or possibly recessed into thelink. The pin may be driven back into a recess in the aperture of thelink, or may cause the link itself to plastically deform. In oneembodiment, the pin extends out from the surface of the link by lessthan 10% of the thickness of the link. In another embodiment, the pinextends out from the surface of the link by less than 50% of thethickness of the link. While other amounts of projection are possible,the intent of the invention is to limit the projection of the pins inorder to promote the advantages of the invention, which include, forexample, the decrease in chain width.

When the pin is set in the link, the pin may be asymmetrically locatedwith respect to the transverse direction of the chain. That is, the pinprojects more to one side of the chain than to the other side across thewidth of the chain assembly.

A second method of manufacture is illustrated in FIG. 13. In thatmethod, the pin is driven into a recess in the aperture in the link. Therecess is sufficient to allow the maintenance of the above-describeddesired relationships of pin projection from the edge of the link.

A third method of manufacture is illustrated in FIG. 14. In that method,the pin is recessed in the aperture and a weld 56 is placed over the pinto maintain its position in the link. As Shown in FIG. 14A, welding isused in conventional links of the prior art to maintain the pin in thelink, but the weld also projects outward from the link. In the presentinvention, as shown in FIG. 14B, the weld is located in the recessbetween the top of the pin and the outside edge of the link and thus theprojection of the weld beyond the outside edge of the link is minimized.Other means of bonding or securing the pin, such as chemical treatments,are also contemplated by the present invention.

The present invention finds particular application with modular chainassemblies. However, it must be emphasized that the modular chainassemblies described herein are not limited to use with minimal pinprojection or the other aspects of the present invention and,accordingly, have much broader applications to both phased andnon-phased chain systems.

Examples of modular chain systems of the present invention are shown inFIGS. 3, 4, and 5. The modular systems are built on the principle of thecombination of two chains to provide a phased system. In a non-phasedsystem, modular chain systems are used to construct a chain system of aspecified width from two or more chains of lesser width.

In the prior art construction of chain systems, and particularly phasedsystems, the two or more chains of the system were typically of the samewidth. Thus, two chains of X/2 width were typically combined to providea chain system of X Width, where X is the number of links across a givenguide row in the chain, whether or not the system was phased. The twochains that together comprise the prior art systems are typically ofequal width. Equal width chains are used in the prior art in order toassure equal load distributions across the width of the entire chainassembly.

As a result, the assembly of a wider system requires two chains toachieve a width of (X+1) links. For example, standard chain systemassemblies are 0.750 inch, 0.875 inch and 1.00 inch. Assembly of each ofthese widths adds one additional link to each guide row. (Similarly, oneadditional link is added to each non-guide row.) Assembly of the nextstandard width requires two chains that achieve a width of (X+2) links.Accordingly, assembly of chain systems of three standard widths requiresassembly of chain systems of three different widths (X, X+1, X+2).

In constructing these systems with two chains, the chains need to be ofwidths of X/2 or 1/2(X+1) or 1/2(X+2) number of links in the guide row.Thus, three different length chains were required to manufacture thethree standard chain systems.

The modular chain systems of the present invention overcome thesedisadvantages by making the chains that form the system of differentwidths. Thus, the two chains that form the combined system are of twodifferent widths that, when combined in a system, make a chain of thedesired width.

In the present invention, two modular chains are formed of width A,which equals X/2 number of links in the guide row, and width B, whichequals 1/2(X+2) number of links in the guide row. These two modularchains, A and B, are used in lieu of the three chains described above(X, X+1, X+2). These two modular chains, A and B, provide the correctnumber of links to achieve the combined systems of the chains usingequal width chains of widths X, X+1, or X+2.

The modular chains are shown in FIGS. 3, 4 and 5 to achieve the standardsystems of 0.750 inch, 0.875 inch, and 1.00 inch. In FIG. 3, the 0.750inch chain 60 is formed by combining two chains 62 of width A. In FIG.4, the 0.875 inch chain 64, which requires an additional link in eachguide row and each non-guide row, is formed by combining a chain 62 ofwidth A with a chain 66 of width B. In FIG. 5, the 1.00 inch chain 68,which requires yet one more additional link in each guide row and eachnon-guide row, is formed by combining two chains 66 of width B. In thismanner, the three standard chain systems are constructed using twomodular chains of widths A and B in lieu of three equal width chains.

Using the formula described above, the three chains of widths of 6 links(FIG. 3), 7 links (FIG. 4) and eight links (FIG. 5), in the non-guiderow, are formed of two modular chains of 3 links (width A) and 4 links(width B), instead of three chain widths.

Substantial savings in manufacturing can be realized by the use of theabove-described modular chain systems. The use of the modular systemsreduces manufacture, assembly and inventory of chains by approximatelyone third by needing only two modular chains, where previously threechains were necessary. The modular chain systems of the presentinvention may be applied to non-phased systems as well as phasedsystems. Similarly, the modular chain systems may be applied to anystandard chain systems which are constructed by adding one additionallink to the width of the chain. The present invention is not limited tothe standard sizes that are presented above as examples.

The modular systems of the present invention may also be used with theminimum pin projection features of the present invention, asdemonstrated in FIG. 6. The modular chains 62, 66 of widths A and B arecombined in FIG. 6 with the minimum or zero pin projection feature. Thereduction in the width of the chain is shown in comparison in FIG. 7(not to scale), which shows the prior art version of the same chainsystem with two chains of equal width and pins projecting from bothsides of the chains of the system.

Thus, the minimal pin projection feature of the present invention allowstwo chains of a system to be placed in a narrower width package byplacing the chains in closer side-by-side proximity. In one embodiment,the guide links of the two side-by-side chains are allowed to contactone another during operation of the chain system. Alternatively, theminimal pi_(n) projection feature of the present invention allowsplacement of a chain with a greater number of links across the chain inthe same width package as the prior art chain. By placing the two chainsin closer proximity, a greater number of links can be placed across thechain. A greater number of links across the width of the chain typicallyprovides a chain of greater strength than a chain of fewer number oflinks placed across the width of the chain.

The features of the present invention find application most prominentlyin the high speed chain applications for automotive engine timing andtransfer case or transmission chains. Examples are shown in FIGS. 10 and11 of use in engine timing chain systems with a single camshaft and withtwo overhead camshafts. Other timing systems applications are possiblewith various timing systems configurations such as those shown inapplication Ser. No. 08/131,473, filed Oct. 4, 1993.

FIGS. 10 and 11illustrate two configurations of phased timing systems.In FIG. 10, the engine timing system 200 includes one driving sprocketsystem 202 located on the crankshaft 203 and one driven sprocket system204 located on the camshaft 205. Rotation of the crankshaft causesrotation of the camshaft through the chain 206 and sprocket system. Thecrankshaft sprocket 202 has one-half the number of teeth of the camshaft204 sprocket. The camshaft typically controls the valve train operationthrough hydraulic lifters and rocker arms connected to the valve stems.

In order to implement the phased system, the crankshaft sprocket andcamshaft sprocket are each replaced by pairs of sprockets 208, 210 thatare offset by one-half pitch. Two side-by-side chains 212, 214 areplaced on the sprockets in the phased relationship.

In the embodiment illustrated in FIG. 11, the engine timing systemutilizes a crankshaft 216 connected to two overhead camshafts 218, 220by a pair of chain systems, 222, 224. If only the crankshaft sprocketsare phased, then two offset sprockets are placed on crankshaft in aphased relationship. Each chain 222, 224 is connected to a singlesprocket 228, 230 on each of the two overhead camshafts. If the camshaftsprockets are also phased, then two offset sprockets are placed on eachoverhead camshaft in a phased relationship. Four sprockets are then usedon the crankshaft. Four chains connect the four sprockets on thecrankshaft with the two sprockets on each camshaft. Two of thecrankshaft sprockets 232, 234 can be phased by one half pitch with theother two crankshaft sprockets, or all four sprockets can be phased byone quarter pitch. The chain systems include tensioners 236, 238 on theslack side of each chain to maintain chain tension and snubbers 240, 242on the tight side of each chain to control chain movement duringoperation.

The features of the present invention also find application in otherchain applications, such as those with rocker joint apertures and CVTtransmission chains.

While several embodiments of the invention are illustrated, it will beunderstood that the invention is not limited to these embodiments. Thoseskilled in the art to which the invention pertains may makemodifications and other embodiments employing the principles of thisinvention, particularly upon considering the foregoing teachings.

What is claimed is:
 1. A silent chain assembly, comprising:a pluralityof interleaved sets of links, pivot members connecting adjacent sets oflinks, each link having a pair of apertures for receiving said pivotmembers, some of said sets of links including inside links, each of saidinside links having at least one depending tooth adapted to contact theteeth of a sprocket, said inside links being constructed to permitarticulation of said inside links with respect to said pivot members,some of said sets of links having at least one guide link at aninnermost portion of said sets and an outer link at an outermost portionof said sets, said guide links having said pivot members extendingthrough at least a portion of said apertures of said guide links, saidpivot members extending from beyond an edge of said guide link to beyondan edge of said outer link in said guide sets of links, said pivotmember extending a greater distance beyond said edge of said outer linkthan the distance said pivot member extends beyond said edge of saidguide link.
 2. The chain assembly of claim 1 wherein said outer link isa guide link.
 3. The chain assembly of claim 1 wherein said outer linkincludes a pair of depending teeth.
 4. The chain assembly of claim 3wherein said pivot member is press fit within said outer link.
 5. Thechain assembly of claim 1 wherein said guide sets include inside linksbetween said guide link and said outer link.
 6. The chain assembly ofclaim 1 wherein said guide link is of a first thickness, said pivotmember extending beyond said edge of said guide link by an amount lessthan 10% of said first thickness of said guide link.
 7. The chainassembly of claim 1 wherein said guide link is of a first thickness,said pivot member extending beyond said edge of said guide link by anamount less than 50% of said first thickness of said guide link.
 8. Thechain assembly of claim 1 wherein said guide link is thinner than saidinside links.
 9. The chain assembly of claim 1 wherein said outer linkis thinner than said inside links.
 10. A silent chain assembly,comprising:a plurality of interleaved sets of links, pivot membersconnecting adjacent sets of links, each link having a pair of aperturesfor receiving said pivot members, some of said sets of links includinginside links, each of said inside links having at least one dependingtooth adapted to contact the teeth of a sprocket, said inside linksbeing constructed to permit articulation of said inside links withrespect to said pivot members, some of said sets of links having atleast one guide link at an innermost portion of said sets and an outerlink at an outermost portion of said sets, said guide links having saidpivot members extending only to a point within said apertures of saidguide links.
 11. The chain assembly of claim 10 wherein said pivotmember is substantially flush with the outside edge of said guide link.12. A silent chain and sprocket assembly, comprising:first and secondchains, each of said chains having a plurality of interleaved sets oflinks, said chains being in side-by-side relationship around sets ofsprockets, each chain having an inner portion that is located closest tothe other chain and an outer portion located on the opposite side ofsaid chain from said inner portion, each chain having pivot membersconnecting adjacent sets of links, each link having a pair of aperturesfor receiving said pivot members, each chain having some of said sets oflinks including inside links, each of said inside links having at leastone depending tooth adapted to contact the teeth of a sprocket, saidinside links being constructed to permit articulation of said insidelinks with respect to said pivot members, each of said chains havingsome of said sets of links with at least one guide link at said innerportion of said chain and an outer link at an outer portion of saidchain, said guide links having said pivot members extending through atleast a portion of said apertures of said guide links, said pivotmembers extending from said pivot members extending from beyond an edgeof said guide link to beyond an edge of said outer link in said sets oflinks having guide links, at least some of said guide links of saidfirst chain contacting at least some of said pivot members of saidsecond chain as said chains transverse said sprockets during operation,and said pivot members of said second chain contacting said guide linksof said first chain at a location along said guide links between saidpivot members of said first chain.
 13. The chain and sprocket assemblyof claim 12 wherein said pivot member extends a greater distance beyondsaid edge of said outer link than the distance said pivot member extendsbeyond said edge of said guide link.
 14. The chain and sprocket assemblyof claim 12 wherein said chain and sprocket assembly furthercomprises:first and second driving sprockets connected to a drivingshaft, said first and second driving sprockets having a plurality ofspaced teeth, said driving sprockets being disposed in parallelrelationship along said drive shaft, the location of said teeth of saidfirst driving sprocket being circumferentially offset with respect tothe teeth of said second driving sprocket, first and second drivensprockets connected to a driven shaft, said first and second drivensprockets having a plurality of spaced teeth, said driven sprocketsbeing disposed in parallel relationship along said driven shaft, thelocation of said teeth of said first driven sprocket beingcircumferentially offset with respect to the teeth of said second drivensprocket, said drive shaft being operatively connected to a power inputand said driven shaft being operatively connected to a power output,said first driving sprocket being aligned with said first drivensprocket and having said first chain drivingly connecting said firstdriving sprocket with said first driven sprocket, said second drivingsprocket being aligned with said second driven sprocket and having asecond chain drivingly connecting said second driving sprocket with saiddriven sprocket.
 15. The chain and sprocket assembly of claim 14 whereinsaid first and second driving sprockets are offset by approximatelyone-half pitch.
 16. The chain and sprocket assembly of claim 14 whereinsaid guide links of said first chain and said guide links of said secondchain travel in a groove located between said first and second drivingsprockets.
 17. The chain and sprocket assembly of claim 14 wherein saidpivot member extends a greater distance beyond said edge of said outerlink than the distance said pivot member extends beyond said edge ofsaid guide link.
 18. The chain and sprocket assembly of claim 14 whereinsaid first and second chains include guide links along the outerportions of each of said chains.
 19. A silent chain and sprocketassembly, comprising:first and second chains, each of said chains havinga plurality of interleaved sets of links, said chains being inside-by-side relationship around sets of sprockets, each chain having aninner portion that is located closest to the other chain and an outerportion located on the opposite side of said chain from said innerportion, each chain having pivot members connecting adjacent sets oflinks, each link having a pair of apertures for receiving said pivotmembers, each chain having some of said sets of links including insidelinks, each of said inside links having at least one depending toothadapted to contact the teeth of a sprocket, said inside links beingconstructed to permit articulation of said inside links with respect tosaid pivot members, each of said chains having some of said sets oflinks with at least one guide link at said inner portion of said chainand an outer link at an outer portion of said chain, said guide linkshaving said pivot members extending through at least a portion of saidapertures of said guide links, said pivot members extending from beyondan edge of said guide link to beyond an edge of said outer link in saidguide sets of links, at least some of said pivot members of said firstchain contacting at least some of said guide links of said second chainas said chains transverse said sprockets during operation.
 20. The chainand sprocket assembly of claim 19 wherein at least some of said guidelinks of said first chain contact at least some of said guide links ofsaid second chain as said chains transverse said sprockets duringoperation.
 21. The chain and sprocket assembly of claim 19 wherein atleast some of said pivot members of said second chain contact at leastsome of said guide links of said first chain as said chains transversesaid sprockets during operation.
 22. The chain and sprocket assembly ofclaim 19 wherein said chain and sprocket assembly furthercomprises:first and second driving sprockets connected to a drivingshaft, said first and second driving sprockets having a plurality ofspaced teeth, said driving sprockets being disposed in parallelrelationship along said drive shaft, the location of said teeth of saidfirst driving sprocket being circumferentially offset with respect tothe teeth of said second driving sprocket, first and second drivensprockets connected to a driven shaft, said first and second drivensprockets having a plurality of spaced teeth, said driven sprocketsbeing disposed in parallel relationship along said driven shaft, thelocation of said teeth of said first driven sprocket beingcircumferentially offset with respect to the teeth of said second drivensprocket, said drive shaft being operatively connected to a power inputand said driven shaft being operatively connected to a power output,said first driving sprocket being aligned with said first drivensprocket and having said first chain drivingly connecting said firstdriving sprocket with said first driven sprocket, said second drivingsprocket being aligned with said second driven sprocket and having asecond chain drivingly connecting said second driving sprocket with saiddriven sprocket.